A new species of Ischnocnema is described from Serra da Mantiqueira, Municipality of Campos do Jordao, State of São Paulo, Brazil. The new species is a member of the Ischnocnema lactea Species Series. The new species differs from other species in the Ischnocnema lactea Species Series by its small size, snout sub-elliptical in dorsal view and acuminate-rounded in lateral view, and advertisement call. Descriptions of the dorsal coloration, advertisement call, and natural history are presented.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)